/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.channel.socket.nio;

import io.netty.channel.ChannelException;
import io.netty.channel.socket.DatagramChannelConfig;
import io.netty.channel.socket.DefaultDatagramChannelConfig;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.SocketUtils;

import java.lang.reflect.Method;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.nio.channels.DatagramChannel;
import java.util.Enumeration;

/**
 * The default {@link NioDatagramChannelConfig} implementation.
 */
class NioDatagramChannelConfig extends DefaultDatagramChannelConfig
{

    private static final Object IP_MULTICAST_TTL;

    private static final Object IP_MULTICAST_IF;

    private static final Object IP_MULTICAST_LOOP;

    private static final Method GET_OPTION;

    private static final Method SET_OPTION;

    static
    {
        ClassLoader classLoader = PlatformDependent
                .getClassLoader(DatagramChannel.class);
        Class<?> socketOptionType = null;
        try
        {
            socketOptionType = Class.forName("java.net.SocketOption", true,
                    classLoader);
        }
        catch (Exception e)
        {
            // Not Java 7+
        }
        Class<?> stdSocketOptionType = null;
        try
        {
            stdSocketOptionType = Class.forName(
                    "java.net.StandardSocketOptions", true, classLoader);
        }
        catch (Exception e)
        {
            // Not Java 7+
        }

        Object ipMulticastTtl = null;
        Object ipMulticastIf = null;
        Object ipMulticastLoop = null;
        Method getOption = null;
        Method setOption = null;
        if (socketOptionType != null)
        {
            try
            {
                ipMulticastTtl = stdSocketOptionType
                        .getDeclaredField("IP_MULTICAST_TTL").get(null);
            }
            catch (Exception e)
            {
                throw new Error("cannot locate the IP_MULTICAST_TTL field", e);
            }

            try
            {
                ipMulticastIf = stdSocketOptionType
                        .getDeclaredField("IP_MULTICAST_IF").get(null);
            }
            catch (Exception e)
            {
                throw new Error("cannot locate the IP_MULTICAST_IF field", e);
            }

            try
            {
                ipMulticastLoop = stdSocketOptionType
                        .getDeclaredField("IP_MULTICAST_LOOP").get(null);
            }
            catch (Exception e)
            {
                throw new Error("cannot locate the IP_MULTICAST_LOOP field", e);
            }

            Class<?> networkChannelClass = null;
            try
            {
                networkChannelClass = Class.forName(
                        "java.nio.channels.NetworkChannel", true, classLoader);
            }
            catch (Throwable ignore)
            {
                // Not Java 7+
            }

            if (networkChannelClass == null)
            {
                getOption = null;
                setOption = null;
            }
            else
            {
                try
                {
                    getOption = networkChannelClass
                            .getDeclaredMethod("getOption", socketOptionType);
                }
                catch (Exception e)
                {
                    throw new Error("cannot locate the getOption() method", e);
                }

                try
                {
                    setOption = networkChannelClass.getDeclaredMethod(
                            "setOption", socketOptionType, Object.class);
                }
                catch (Exception e)
                {
                    throw new Error("cannot locate the setOption() method", e);
                }
            }
        }
        IP_MULTICAST_TTL = ipMulticastTtl;
        IP_MULTICAST_IF = ipMulticastIf;
        IP_MULTICAST_LOOP = ipMulticastLoop;
        GET_OPTION = getOption;
        SET_OPTION = setOption;
    }

    private final DatagramChannel javaChannel;

    NioDatagramChannelConfig(NioDatagramChannel channel,
            DatagramChannel javaChannel)
    {
        super(channel, javaChannel.socket());
        this.javaChannel = javaChannel;
    }

    @Override
    public int getTimeToLive()
    {
        return (Integer) getOption0(IP_MULTICAST_TTL);
    }

    @Override
    public DatagramChannelConfig setTimeToLive(int ttl)
    {
        setOption0(IP_MULTICAST_TTL, ttl);
        return this;
    }

    @Override
    public InetAddress getInterface()
    {
        NetworkInterface inf = getNetworkInterface();
        if (inf == null)
        {
            return null;
        }
        else
        {
            Enumeration<InetAddress> addresses = SocketUtils
                    .addressesFromNetworkInterface(inf);
            if (addresses.hasMoreElements())
            {
                return addresses.nextElement();
            }
            return null;
        }
    }

    @Override
    public DatagramChannelConfig setInterface(InetAddress interfaceAddress)
    {
        try
        {
            setNetworkInterface(
                    NetworkInterface.getByInetAddress(interfaceAddress));
        }
        catch (SocketException e)
        {
            throw new ChannelException(e);
        }
        return this;
    }

    @Override
    public NetworkInterface getNetworkInterface()
    {
        return (NetworkInterface) getOption0(IP_MULTICAST_IF);
    }

    @Override
    public DatagramChannelConfig setNetworkInterface(
            NetworkInterface networkInterface)
    {
        setOption0(IP_MULTICAST_IF, networkInterface);
        return this;
    }

    @Override
    public boolean isLoopbackModeDisabled()
    {
        return (Boolean) getOption0(IP_MULTICAST_LOOP);
    }

    @Override
    public DatagramChannelConfig setLoopbackModeDisabled(
            boolean loopbackModeDisabled)
    {
        setOption0(IP_MULTICAST_LOOP, loopbackModeDisabled);
        return this;
    }

    @Override
    public DatagramChannelConfig setAutoRead(boolean autoRead)
    {
        super.setAutoRead(autoRead);
        return this;
    }

    @Override
    protected void autoReadCleared()
    {
        ((NioDatagramChannel) channel).clearReadPending0();
    }

    private Object getOption0(Object option)
    {
        if (GET_OPTION == null)
        {
            throw new UnsupportedOperationException();
        }
        else
        {
            try
            {
                return GET_OPTION.invoke(javaChannel, option);
            }
            catch (Exception e)
            {
                throw new ChannelException(e);
            }
        }
    }

    private void setOption0(Object option, Object value)
    {
        if (SET_OPTION == null)
        {
            throw new UnsupportedOperationException();
        }
        else
        {
            try
            {
                SET_OPTION.invoke(javaChannel, option, value);
            }
            catch (Exception e)
            {
                throw new ChannelException(e);
            }
        }
    }
}
